#include<iostream>
#define M 500
int main(){

  std::cout<< "hello claus" <<std::endl; 
  
  #ifdef N
    std::cout<< "SHOW N" <<std::endl;
  #else 
    std::cout<<"NO N"<<std::endl;
  #endif 

    //测试宏
  std::cout<< M <<std::endl;

  return 0;
}
